Headlight glass or lens



amm@

Dec. '25 1923.

J. SODERBERG HEADIIGHT' GLASS- 0R LENS Original Filed Feb. -8,

` yPatented Deer-25, i923.

- JACOB summarise,por rrrrsnunen: rmsrnvanre, assreNoa'f j intatti ras enr'ra-NrA ferries.,

' rnarnenass contratar, a' CORPORATION or rnNNsYLvnNra.

.applicative eiearetrafye, 19er, serial T o all whom t may concern.'

Be it known that L JACOB g c1t1zen of the United States, and a resident l of-'Pittsburgh, in the county 'of Allegheny andgState of Pennsylvania', have made a new,l and -useful Invention in Headlight Glasses or'Lenses, of which the following is a specification.

. ularl upon automobile lamps. 4 The inven- 4tion as for its principal objects theprovi- ,sion of a lens,

held of illumination of the desired range -l of intensity, free from black spaces onlines,

and vin which the light maybe distributed to the 'bestadvantaga and in accordance `with the generally accepted requirements of lthevarious States, and-(2yin which the prismsurfaces are Vof such a character that the mold for producing them l'may be made or einished by machine'zwerk (rather than by hand chipping), thus'producing mathe# rnaticallyv accurate surfaces lmore cheaply and in a material-'such as stellite or ni- -chrome, which Ais superior for glass casting or mold work" and which otherwise could not be utilized because ofthe diiiculty of Working it'.` Other A.ob'ects and advantages incident to the lens'will be apparent from the accompanying' description and illustra*- tions. One embodimentI of the invention.l iS 'illustrated' in 'the accompanying drawings, Whereinz-f, Y

Figure l is a rear elevation of. the lens; a horizontal section on the line lillll of Figi; Fi .3 is a vertical section on the line lilldill of Fig. l, and t gsva diagonal section onthe line lV' l of 1g. il.. i Y A. -J'- 'llhe idea involved in the c'onstruct-ionfof the improved lens isto startas the basis of the desi with a lens having` concentric anl nular ri ges or prisma-which is the equiva-' lent of a .plano-.concave lens, and modify the angles of the risms sofas to get the desired clistributlon` of Vlight which is reuired uch a lens (before the present improve- .ment'is applied thereto) when 4used with a parabolic relector, spreads the light away from the center or axis of the parabola in all directions.'

As the first step in the design the angles SODER'BERG, a-

- v y which, (l). when used with 'lthe usual parabolic reiector, will givea for automobile o:headlight work.

No. tasca Renewed. November 17.1923. f

is concerned,`.just the right -amount is secured for glvmg the required side lighting.

@This dispersiom'however, is, o f course, n'ot fright in so dis ersoin is concerne Awit respect .tothe u ward 'dispersion as itv is necessary thatl the transmitted: light should not produce an vobjectiona'llle glare far as'the upward and' downward d, and particularly above Ja certainlevel, and further, any viight transmitted allieve that level would be `more or less wasted'since it wouldbe of no eiect in illuminating the roadway. rl`he angle of the prisms'must therefore he sov modified as to turn-the light downwardly,land1this is accomplished 1n my invention by dividingl the 'annularly ribbed lens into horizontal. bands or sections, and tilting' the sections of the annular prisms in the bands in such wayv l aste 'bring the light transmittedthrougheach band at the desired level.'

This' tilting of the various sections or bands vmust be made somewhat greater than would be theoretically called for with a perfect reflector and 'with the light condensed to a point and located. at the focus of the parabola. 'lllhe light filament liesl lboth tothe front and rear of the. reliector focus vso that. g-

' thereVA is an upward and downwarddispersion of th'e light away from .the horizontal plane along'which a beam of light would be theoretically therefore til-ted to bend the rays downward to .a greater, extent` than would be vthe case if the light were concentrated at a point' at the focus of the reiiector, and this is particf transmitted. y'llhe-"bands are y -v-ularlyvthe.. case with" the central bands, as

. the central 'portion of the reflector givesl a greater divergence of rays due to the charportions ofthe reflector'.

' 'llhe angle of tilting of the bands must be determined to acertain extent byvexperi# ment, due `to the condition as above stated With-respect to the lightl filament, so that the theoretical tilting of the various bands maynot conform tothat actually required, and the inventionis not limited.to the tilting of the successive bands according to anyv fixed rule. lin eneral,'the amount oftilting in the various ands fromthe center, both up and down, some cases it might be desirable to make the tilting the same 1n certain bands. 'llhe faces .thelilamentthan does the outer.

will decrease, although in of the'prisms upon the rear side of the lens.

, y porting 'fixture,' after which strips lof metal rectangular in cross section areyfitted into the grooves and machined to a plane surface upon their rear faces. After this the `annular grooves are turned or ground in a lathe upon the plane surface' asabove produced.

rll`he annular strips are thenremovedand the sides of the strips opposite to theside carrying the annular grooves are secured-,to a flat` surface'constituting the body portion of thel plunger. The'ability to produce this lplunger by machine work is a. great advantage since it permits theA plunger to be made` of excessively hard material, such as stellite or nichrome. These materials will last a long time in casting operations without requiring re-surfacing, and the material, because of its smoothness and durability, gives a -better ysurface to the glass than is the case with the cast iron mold. These are advantages not 'possessed by' molds of such irregular contour that they must be formed by hand chipping and working. `Suchmolds must necessarily be of relatively soft composition,

such as cast iron. Molds of such lmaterial require frequent re-surfa'cing, involving a largev itemofexpense, and 1n many cases `Changing the angles of the prisms. v 5

Referring now tothe drawings, l is the edge or holding portion of the lens for fitting into the casing,A of the lamp, and 2, 3, 4, 5 and 6 (Fi 2) are annular prisms or ridges which divi e the rear face of the lens into a plurality of annular bands. As indicated in ig. 2, which shows the normal angle of the prisms, that is the anglebefore the tilting in horizontal bands heretofore referred to, such prisms are at sufficient angle to bend the parallel rays from a parabolic reflector passtribution desired, as well as other practical' ing therethrough, outwardly, to give the necessary side lighting. In order to giye this dispersed light the necessary downward inclination to avoid glare and get the desired illumination on the roadway, the-rear face of the lens is divided into the horizontal change, depending upon the size of the lens required and upon the character of the dis,-

considerations. These bands are tilted at varying angles as will be seen from Fig. 3,

L11-raser lens up and down. The increased angle at the-center is ldue to the fact that a part of lthe central rays diverge more than those rays.,

of 'the bands above the axis A' of the lens and of the reflector, since these upwardly diverging rays are most objectionable be- "cause of the glare produced, while the rays from the lower half ofthe lens are bent downwardly anyway because of the inclinationof the annular prisms, but at the same time the bending of the light passing through the lens just below fthe center is important since the lateral dispersion is so great that the side illumination from such portion of theA lens is too far to the sid'e'and has little utility.- By .bending this light down sharply it. is brought closer to the car and nearertothecenter of illumination. a The angles as illustrated in the various sections are-exaggerated inv order to more clearly illustrate the principle involved, which principle, as well as the peculiar and Varying angles, will be readily understood by an inspection of Fig. 3 in connection with Fig. 4l, the latter being taken on the diagonal plane IV-IV of Fig. l. it will be seen that the amount of tilting from the normal of the Various annular sections lying within any horizontal band is the same. For instance, the annular sections 9a, 9, 9C, 9d and 99,?lying in the horizontal band 9 are all swung from their normal angle the same amount, which is a different amount from that which the sections lying 1n thev adjacent .such angles decreasing from the center of the l horizontal bands 8 and 10 are tilted. This A breaks the face of the lens into a very large number of lenses of varying angles, accomplishing, in addition to the function of bending lthe light downwardly the desired amount, the further function of eliminating -any tendency toblack spaces or lines in the surfaces of the molds. may be produced by machine work,

imacat whichare determined upon are, to a certain g extent, a matter of individual judgment, depending upon the iield of illumination desired and upon the requirements of the law. In some cases it may be desirable to bend the light downward more than in others, and to secure a field of illumination which has its maximum intensity at a point nearer to theA car than in'other eases. There is, therefore, no intent to limit the invention to the par-v ticular range of angles illustrated and described, although such illustration and de.

scription are intended to indicate the best method of embodying vthe invention. As heretofore indicated, the bending downwardly of the rays transmitted lthrough the upper portion of the lens is most important, so thata wider variation or departure from the construction illustrated is permissible in the lower-portion of the lens than in the upper4 portion, although, as heretofore stated, it is desirable to bend thel rays from this portion of the lens downward and particularly that portion transmitted `nearest the center. The invention is also not limited to tilting an entire horizontal band at the same'angle throughout, as in some cases it might be desirable to divide the band into a plurality of `sections and tilt these sections differently. What I claim is: Y

1. In combination in a headlight or cover glass for use with a parabolic reflector, a

plate of glass having on one side a series of annular prisms, into a plurality of horizontal bands with the prisms being .the transmitted rays such prisms being divided portions of the prisms in each band tilted about horizonte axes to turn the transmitted rays downwardly.

2. In combination in a headlight or cover lass for use with .a parabolic reflector, a on one side a series of plate of glass havin I divided annular prisms, suci prisms being into a plurality of horizontal bands with the portions of the prisms in each band similarly tilted about horizontal axes to turn the transmitted rays downwardly, but with lvarying anglesof` tilting for the di`erent bands.

3.- In combination in a headlight or cover glass for use with a parabolic reflector, a plate of glass havin on one side a series of annular prisms, sui prisms being divided into Ia plurality of horizontal bands with the portionsof the prisms in each band similarly tilted about horizontal axes 'to turn the transmitted rays downwardly, but with varying angles of tilting ,ford the different bands, and with the degree of tilting decreasing from the center of the lens up and down.

4. In combinatin in a headlight or cover lass for use with a parabolic reiiector, a

plate of glass having on one side a series of annular prisms of varyin angles for bending the transmitted para lel rays from the reflector away from the axis thereof, such divided .into a plurality of horizontal bands with portions of the prisms in each of ing degrees about horizontal axes to turn downwardly.

In testimony whereof, I have hereunto subscribed my name this 2nd day of February, 1921.

' JACOB SODERBERG.

such bands tilted at vary- A 

